NOT-FOR-MERGING: add run-realm-tests

Until we add support for KVMTOOL to run the tests using the
scripts, provide a temporary script to run all the Realm tests.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>